1. Field
Embodiments of the present disclosure relate to a tension and compression tester for a fracture stress test of a compact pipe sample, and more specifically, to a tension and compression tester for a fracture stress test of a compact pipe, which is capable of conducting both tension and compression tests while applying loads on the sample with ease through a lever during the fracture stress test of the compact pipe sample.
2. Description of Related Art
It is necessary to obtain the fracture stress of pipe system structure to apply Leak Before Break (LBB) design concept on the pipe system structure such as a nuclear power plant which can generate considerable problems in the society once emergency occurs.
However, it is practically difficult to conduct a full-scale test, considering that it takes numerous pipes and testers to conduct tests, and subsequently requires increased costs and time to obtain the fracture stress of the pipe system structure.
It has been thus suggested to obtain the fracture stress of a material using standard sample tests and evaluate the fracture stress of the pipe system structure based on the obtained fracture stress, rather than testing with numerous pipes and tests.
That is, the American Society for Testing and Materials (ASTM) suggested the Compact Tension (CT) or Single Edge Notched Bending (SENB) sample as a standard sample.
While the standard samples like those mentioned above can provide advantage of standardized sample shapes and testing methods, there is also a limit in the manufacture of the sample due to pipe curvatures and thicknesses.
Further, to obtain the fracture stress, it is necessary to consider the constraint effects from the geometric shapes or dimensions of the sample, and the influence of the constraint effect is greater on the structure like piping. It is accordingly necessary to adjust the constraint effect even when the test is conducted with the standard sample.
Meanwhile, a miniature pipe sample has been devised using portions taken from the real pipes, based on the pipe curvature, thickness, etc. to eliminate need for adjustment of constraint effect influence which is generated due to changes in the size and shape of the sample. However, the sample and the lever deformed during loading, which in turn caused variations in the test results. Further, spacing between the lever and holder or sample caused insufficient loading during loading process.
Further, the existent fracture stress tester for a pipe sample is disadvantageous because it is designed in consideration of loading either in the tension direction or in the compression direction only, and thus can conduct only one type of test. Accordingly, a tester is necessary, which can deliver all of the tension, compression, and bending received from the loader and the lever to the pipe sample during the pipe fracture stress test.